EA just sent out a press release that said there will also be an in-game exclusive item for PC owners who buy the game through EA's Origin digital distribution channel. Here are the details on the item:

AT-12 Raider Shotgun

The AT-12 Raider Shotgun fires a large pellet spread, ensuring maximum coverage for close-range targets. Designed for superior rapid fire, the AT-12 allows for optimal recovery time between shots.

GameStop issued a press release today detailing the in-game exclusives. Gamers who pre-order Mass Effect 3 with the retailer will receive a code on their receipt that will later be used to redeem the N7 Valkyrie Assault Rifle and the N7 Defender Armor.

Here are the details on both items, per the press release:

N7 Valkyrie Assault Rifle

After the carnage of the Battle of the Citadel, Alliance officers commissioned a new rifle for their ground forces. A variation of the popular Avenger design, the Valkyrie is now standard issue for new recruits. Exceptionally well-crafted, accurate, and packing ample firepower, the rifle is a hot black-market item on the rare occasion it surfaces.

N7 Defender Armor

The Defender Armor is a variation on the N7 Special Forces’ combat gear, built to protect soldiers in long-running engagements where reinforcements may be sparse. When the wearer fires a weapon, the suit's computers divert energy from the main power cell to the gun's kinetic coils, offering an extra punch. The Defender's storage compartments are designed to hold spare thermal clips, while capacitors throughout the armor provide extra power to shields during critical moments in battle. The armor also comes with an injection system built into the suit and neural-linked bio-monitors that help adjust the wearer's breathing rate and adrenaline levels.